Tapped out Brian Fagan, Brian Fagan is emeritus professor of anthropology at UC Santa Barbara and the author of "The Great Warming: Climate Change and the Rise and Fall of Civilizations."

Fix Chad to save Darfur Korinna Horta and Delphine Djiraibe, Korinna Horta is a senior economist for the Environmental Defense Fund. Delphine Djiraibe is an attorney for the Chadian Assn. for the Promotion and Protection of Human Rights.